A Passive Sweat-Responsive Thermoregulatory Textile with the Largest Thermal Comfort Zone

Maintaining the human body temperature within the thermally comfortable range under volatile temperatures and environments is critical from both the perspectives of human health and energy saving. Therefore, developing thermoregulatory textiles that have a large comfort zone in response to complex environmental temperature changes has been persistently pursued. Here, we demonstrate that a passive sweat-responsive thermoregulatory (PSRT) textile, composed of a unidirectional liquid-transported polycaprolactam (PA6)/metal bilayer, can tune mid-infrared (MIR) radiation and sweat evaporation simultaneously, thus achieving a substantial expansion of the thermal comfort zone in response to dynamic conditions. Specifically, for heating mode, the metalized bilayer PSRT textile intrinsically possesses low emissivity (ε_MIR ∼0.233) for excellent radiative heating. As the environmental temperature increases or during heavy exercise, sweat secretion by the skin increases rapidly, which triggers the autonomous switch to the cooling mode. Sweat rapidly transports to the top PA6 layer, facilitating rapid evaporation through the unidirectional liquid transport design; meanwhile, the PSRT textile automatically switches from low emissivity to high emissivity (ε_MIR ∼0.955) for radiative cooling. As a result, this PSRT textile expands the thermal comfort zone by 24.7 °C (8.3-33.0 °C), setting a performance record among passive thermoregulatory textiles. It is expected that the further advancement of the passive sweat-responsive thermoregulatory textile with an increasing thermal comfort zone can not only provide comfort for the human body with a minimized carbon footprint but also significantly expand the geographic and seasonal restrictions of human activity.